The present invention is directed to a new and improved apparatus for use in turning steerable vehicle wheels in response to rotation of a steering wheel. The apparatus includes first and second hydraulic motors which are connected with the steerable vehicle wheels.
Steerable vehicle wheels have previously been turned by a rack and pinion steering system. The rack and pinion steering system may include a hydraulic motor which is connected with the steerable vehicle wheels in the manner disclosed in U.S. Pat. No. 3,709,099. Other known rack and pinion steering systems are disclosed in U.S. Pat. Nos. 4,887,683 and 5,851,015.
Steerable vehicle wheels have also been turned by steer-by-wire steering systems. In a known steer-by-wire steering system, there has been no mechanical connection between a steering wheel and a steering apparatus connected with steerable vehicle wheels. In at least one known steer-by-wire steering system, a transmitter assembly associated with a steering wheel sends a signal to a receiver assembly associated with a steering apparatus connected with the steerable vehicle wheels. This steering apparatus is actuated in accordance with the signal received by the receiver assembly. Known steer-by-wire steering systems are disclosed in U.S. Pat. Nos. 6,546,322 and 6,655,709.